USB-2001-TC
USB-based Thermocouple Input
User's Guide
Document Revision 6A
November 2014
© Copyright 2014
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Notice
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into the body, or b) support or sustain life and whose failure to perform can be reasonably expected to result in
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HM USB-2001-TC.docx
Table of Contents
Preface
About this User's Guide ....................................................................................................................... 4
What you will learn from this user's guide ......................................................................................................... 4
Conventions in this user's guide ......................................................................................................................... 4
Where to find more information ......................................................................................................................... 4
Chapter 1
Introducing the USB-2001-TC .............................................................................................................. 5
Functional block diagram ................................................................................................................................... 5
Chapter 2
Installing the USB-2001-TC .................................................................................................................. 6
Unpacking the USB-2001-TC ............................................................................................................................ 6
Installing the software ........................................................................................................................................ 6
Installing the hardware ....................................................................................................................................... 6
Chapter 3
Functional Details ................................................................................................................................. 7
Components ........................................................................................................................................................ 7
Thermocouple input .......................................................................................................................................................... 7
USB connector .................................................................................................................................................................. 8
LED indicator ................................................................................................................................................................... 8
Analog input circuitry ......................................................................................................................................... 8
Open-thermocouple detection (OTD) ............................................................................................................................... 8
Thermocouple measurement accuracy................................................................................................................ 9
Cold-junction temperature measurement accuracy ........................................................................................................... 9
Mechanical drawings .......................................................................................................................................... 9
Chapter 4
Specifications ......................................................................................................................................10
Channel configurations ..................................................................................................................................... 10
Compatible thermocouples ............................................................................................................................... 11
Temperature accuracy....................................................................................................................................... 11
LED indicator ................................................................................................................................................... 14
Power ................................................................................................................................................................ 14
Safety voltages .................................................................................................................................................. 15
Bus interface ..................................................................................................................................................... 15
Mechanical ....................................................................................................................................................... 15
Environment ..................................................................................................................................................... 15
Declaration of Conformity ..................................................................................................................16
3
Preface
About this User's Guide
What you will learn from this user's guide
This user's guide describes the Measurement Computing USB-2001-TC data acquisition device and lists device
specifications.
Conventions in this user's guide
For more information
Text presented in a box signifies additional information and helpful hints related to the subject matter you are
reading.
Caution! Shaded caution statements present information to help you avoid injuring yourself and others,
damaging your hardware, or losing your data.
bold text
Bold text is used for the names of objects on a screen, such as buttons, text boxes, and check boxes.
italic text
Italic text is used for the names of manuals and help topic titles, and to emphasize a word or phrase.
Where to find more information
Additional information about USB-2001-TC hardware is available on our website at www.mccdaq.com. You
can also contact Measurement Computing Corporation with specific questions.
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Knowledgebase: kb.mccdaq.com
Tech support form: www.mccdaq.com/support/support_form.aspx
Email: [email protected]
Phone: 508-946-5100 and follow the instructions for reaching Tech Support
For international customers, contact your local distributor. Refer to the International Distributors section on our
website at www.mccdaq.com/International.
4
Chapter 1
Introducing the USB-2001-TC
The USB-2001-TC is a USB 2.0 full-speed device that provides one thermocouple input channel.
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Thermocouple types J, K, R, S, T, N, E, and B are supported. The thermocouple type is software
programmable and stored on the device. A 20-bit ADC processes the data conversions.
Thermocouple input ranges are ±73.125 mV (calibrated) and ±146.25 mV, (not calibrated). The
±146.25 mV range is used for open thermocouple detection.
The device has an integrated cold junction compensation (CJC) sensor for thermocouple measurements. An
open thermocouple detection feature lets you detect a broken thermocouple.
The USB-2001-TC was tested for full compatibility with both USB 1.1 and USB 2.0 ports.
The USB-2001-TC is a standalone plug-and-play module which draws power from the USB cable. No external
power is required.
Figure 1. USB-2001-TC
Functional block diagram
USB-2001-TC functions are illustrated in the block diagram shown here.
Figure 2. Functional block diagram
5
Chapter 2
Installing the USB-2001-TC
Unpacking the USB-2001-TC
As with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the device from its packaging, ground yourself using a wrist strap or by simply
touching the computer chassis or other grounded object to eliminate any stored static charge.
Contact us immediately if any components are missing or damaged.
Installing the software
Refer to the device product page on the Measurement Computing website for information about the included
and optional software supported by the USB-2001-TC.
Install the software before you install your device
The driver needed to run the USB-2001-TC is installed with the software. Therefore, you need to install the
software package you plan to use before you install the hardware.
Installing the hardware
To connect the USB-2001-TC to your system, connect a USB cable from the USB connector to either a USB
port on the computer or to an external USB hub connected to the computer. No external power is required.
If the LED turns off
If the LED is on but then turns off, the computer has lost communication with the USB-2001-TC. To restore
communication, disconnect the USB cable from the computer, and then reconnect it. This should restore
communication, and the LED should turn on.
6
Chapter 3
Functional Details
Components
The USB-2001-TC has the following components:
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Thermocouple input
USB cable and connector
LED indicator
Thermocouple input
You can connect one thermocouple to a standard thermocouple subminiature connector. Thermocouple types J,
K, R, S, T, N, E, and B are supported. The thermocouple type you select will depend on your application needs.
Review the temperature ranges and accuracies of each type to determine which thermocouple is best suited for
the application.
Connect the positive lead of the thermocouple to the TC+ terminal, and the negative lead of the thermocouple to
the TC– terminal.
Figure 3. TC input terminals
If you are unsure which of the thermocouple leads is positive and which is negative, check the thermocouple
documentation or the thermocouple wire spool.
Figure 4. Connecting a thermocouple
For best results, use insulated or ungrounded thermocouples when possible. If you need to increase the length of
your thermocouple, use the same type of thermocouple wires to minimize the error introduced by thermal
EMFs.
Temperature measurement errors depend in part on the thermocouple type, the temperature being measured, the
accuracy of the thermocouple, and the cold-junction temperature.
Thermocouple with bare wire leads
If your thermocouple has bare wire leads, you can purchase a screw terminal subminiature connector to use with
the USB-2001-TC. These are available from a number of suppliers, such as Nanmac Corporation
(www.nanmac.com). For the best accuracy, the subminiature connector type and thermocouple type should
match.
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USB-2001-TC User's Guide
Functional Details
Figure 5 shows the screw terminal connector wiring.
Figure 5. Screw terminal connector wiring
USB connector
The USB connector provides +5 V power and communication. The voltage supplied through the USB connector
is system-dependent, and may be less than 5 V. No external power supply is required.
LED indicator
The device LED indicates the communication status, and uses up to 5 mA of current.
LED behavior
Condition
Specification
On – steady green
On – blinking green
Off
The device is powered and ready for operation.
The device is powered, but not yet enumerated by the USB.
The device is not powered or is in USB suspend.
Analog input circuitry
Figure 6 shows the analog input circuitry. The thermocouple channel passes through a differential filter and is
sampled by a 20-bit analog-to-digital converter (ADC).
Figure 6. Analog input circuitry
Open-thermocouple detection (OTD)
The USB-2001-TC is equipped with open-thermocouple detection. With OTD, any open-circuit condition at the
thermocouple sensor is detected by the software. An open channel is detected by driving the input voltage to a
positive value outside the range of the thermocouple output. The software recognizes this as an invalid reading
and returns the value "OTD". During an open thermocouple condition, some invalid values may be returned
before the open thermocouple is reported.
Check the STATUS value before reading temperature values
To ensure that valid temperature readings are returned, verify that the value of STATUS is READY before
taking measurements. Invalid temperature readings may be returned if the STATUS value is BUSY or ERROR.
A value of BUSY indicates that no new data is available. In this condition the same temperature value as
previously read is returned until the STATUS value changes to READY.
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USB-2001-TC User's Guide
Functional Details
Thermocouple measurement accuracy
Cold-junction temperature measurement accuracy
Heat from other nearby heat sources can cause errors in thermocouple measurements by heating up the
terminals so that they are at a different temperature than the cold-junction compensation sensor used to measure
the cold junction.
Minimizing thermal gradients
Thermocouple wire can be a significant source of thermal gradients if it conducts heat or cold directly to
terminal junctions. To minimize these errors, follow these guidelines:
 Use small-gauge thermocouple wire. Smaller wire transfers less heat to or from the measuring junction.
 Avoid running thermocouple wires near hot or cold objects.
Increasing the thermocouple length
If you need to increase the length of your thermocouple, use wires made of the same conductive material to
minimize the error introduced by thermal EMFs.
Mechanical drawings
Figure 7. USB-2001-TC dimensions
9
Chapter 4
Specifications
All specifications are subject to change without notice.
Typical for 25 °C unless otherwise specified.
Caution! Electromagnetic interference can adversely affect the measurement accuracy of this product. The
input terminals of this device are not protected for electromagnetic interference. As a result, this
device may experience reduced measurement accuracy or other temporary performance
degradation when connected cables are routed in an environment with radiated or conducted radio
frequency electromagnetic interference. To limit radiated emissions and to ensure that this device
functions within specifications in its operational electromagnetic environment, take precautions
when designing, selecting, and installing measurement probes and cables.
Analog input
Table 1. Input characteristics
Parameter
Conditions
Specification
Channel-to-USB ground
Channel-to-USB ground
One
20 bits
±73.125 mV, calibrated
±146.25 mV, not calibrated. Used for open
thermocouple detection.
±30 V
>145 dB
Number of channels
ADC resolution
Input ranges
Common-mode range
Common-mode rejection ratio
(0 to 60 Hz)
Noise rejection
Temperature measurement
ranges
Conversion time
Input bandwidth
Differential input impedance
Input noise
Open thermocouple bias voltage
Cold-junction compensation
sensor accuracy
Cold-junction compensation
sensor resolution
Overvoltage protection
50/60 Hz
>80 dB
Works over temperature ranges defined by NIST (J,
K, R, S, T, N, E, and B thermocouple types.) The E
type has a maximum limit of 900 ºC.
250 ms
1 Hz
20 MΩ between isolated 3.3 V and ground
2 µVpp
3.3 V
1.25 °C maximum, 0.6 °C typical
–3 dB
0 to 65 ºC
0.0625 °C typical
30 V max between TC+ and TC–
Channel configurations
Table 2. Channel configuration specifications
Sensor category
Conditions
Specification
Thermocouple (Note 2)
J, K, S, R, B, E, T, or N
One differential channel
Note 1: Channel configuration information is stored in internal FLASH Program Memory on the
microcontroller by the firmware whenever any item is modified. Modification is performed by
commands issued over USB from an external application, and the configuration is non-volatile.
Note 2: The factory default configuration is undefined ‘#’.
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USB-2001-TC User's Guide
Specifications
Compatible thermocouples
Table 3. Compatible sensor type specifications
Parameter
Specification
Thermocouple type
J:
K:
R:
S:
T:
N:
E:
B:
–210 °C to 1200 °C
–270 °C to 1372 °C
–50 °C to 1768 °C
–50 °C to 1768 °C
–270 °C to 400 °C
–270 °C to 1300 °C
–270 °C to 900 °C
0 °C to 1820 °C
Temperature accuracy
The following graphs show the errors for each thermocouple type when connected to the USB-2001-TC. The
graphs display the maximum errors at 25 °C and over the full operating temperature range, and account for
cold-junction compensation errors. The graphs were generated using thermocouples connected to subminiature
connectors of the same type.
The CJC sensor resolution is 0.0625 °C. This is the minimum value of the CJC step width. As such, the reading
may result in a saw tooth curve rather than a square curve as the temperature inside the board changes. This is
the expected behavior.
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USB-2001-TC User's Guide
Specifications
Temperature error of J type thermocouple
Temperature error of K type thermocouple
Temperature error of R type thermocouple
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USB-2001-TC User's Guide
Specifications
Temperature error of S type thermocouple
Temperature error of N type thermocouple
Temperature error of B type thermocouple
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USB-2001-TC User's Guide
Specifications
Temperature error of T type thermocouple
Temperature error of E type thermocouple
LED indicator
Table 4. LED behavior
Condition
Specification
Steady green
Blinking green
Off
The device is powered and ready for operation.
The device is powered, but not yet enumerated by the USB.
The device is not powered or is in USB suspend.
Power
Table 5. Power specifications
Parameter
Specification
Current consumption from USB
Suspend current
Recommended warm-up time
150 mA maximum, 100 mA typical
2.5 mA maximum
15 minutes
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USB-2001-TC User's Guide
Specifications
Safety voltages
Connect only voltages that are within these limits.
Table 6. Safety voltage specifications
Parameter
Conditions
Specification
Isolation
Channel-to-earth ground
+30 V maximum (Note 3)
Note 3: Measurement Category I is for measurements performed on circuits not directly connected to the
electrical distribution system referred to as MAINS voltage. MAINS is a hazardous live electrical
supply system that powers equipment. This category is for measurements of voltages from specially
protected secondary circuits. Such voltage measurements include signal levels, special equipment,
limited-energy parts of equipment, circuits powered by regulated low-voltage sources, and electronics.
Bus interface
Table 7. Bus specifications
Parameter
Specification
USB specification
Device compatibility
USB 2.0 Full-Speed
USB 1.1, USB 2.0
Mechanical
Table 8. Mechanical specifications
Parameter
Specification
Dimensions
62.56 mm (L) x 38.10 mm (W) x 20.32 mm (H)
2.46 in. (L) x 1.50 in. (W) x 0.80 in. (H)
2 meters (6.5 feet)
Approximately 116 g (4.1 oz)
Cable Length
Weight
Environment
Table 9. Environmental specifications
Operating temperature range
Storage temperature range
Operating humidity
Storage humidity
Maximum altitude
Pollution degree
0 to 55 ° C
–40 to 85 ° C
10 to 90% non-condensing
5 to 95% RH, noncondensing
2,000 m (at 25 ºC ambient temperature)
2
Note 4: The USB-2001-TC is intended for indoor use only.
15
Declaration of Conformity
Manufacturer:
Address:
Category:
Measurement Computing Corporation
10 Commerce Way
Suite 1008
Norton, MA 02766
USA
Electrical equipment for measurement, control and laboratory use.
Measurement Computing Corporation declares under sole responsibility that the product
USB-2001-TC
to which this declaration relates is in conformity with the relevant provisions of the following standards or other
documents:
EC EMC Directive 2004/108/EC: General Requirements, EN 61326-1:2006 (IEC 61326-1:2005).
Emissions:
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EN 55011 (2007) / CISPR 11(2003): Radiated emissions: Group 1, Class A
EN 55011 (2007) / CISPR 11(2003): Conducted emissions: Group 1, Class A
Immunity: EN 61326-2-1:2006, Particular requirements for sensitive test and measurement equipment for EMC
unprotected applications.
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IEC 61000-4-2 (2001): Electrostatic Discharge immunity.
IEC 61000-4-3 (2002): Radiated Electromagnetic Field immunity.
IEC 61000-4-4 (2004): Electric Fast Transient Burst Immunity.
IEC 61000-4-5 (2001): Surge Immunity.
IEC 61000-4-6 (2003): Radio Frequency Common Mode Immunity.
IEC 61000-4-11 (2004): Voltage Interrupts.
To maintain compliance to the standards of this declaration, the following conditions must be met.
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The host computer, peripheral equipment, power sources, and expansion hardware must be CE
compliant.
All I/O cables must be shielded, with the shields connected to ground.
I/O cables must be less than 3 meters (9.75 feet) in length.
The host computer must be properly grounded.
Declaration of Conformity based on tests conducted by National Instruments Corporation, Austin, TX , 787593504 USA in November, 2009.
We hereby declare that the equipment specified conforms to the above Directives and Standards.
Carl Haapaoja, Director of Quality Assurance
Measurement Computing Corporation
10 Commerce Way
Suite 1008
Norton, Massachusetts 02766
(508) 946-5100
Fax: (508) 946-9500
E-mail: [email protected]
www.mccdaq.com